This is something I have never done changing from a jet pump to a submersible, I thought I would ask here prior to calling a friend that is a well tester. I was thinking about replacing my jet pump with a submersible but have never done this. Other than the controller for the submersible are there any other issues I should be aware of? I have pulled a bunch of submersible's in the past and repaired / replaced the surface side of jets in the past. I was thinking about changing it for efficiency reasons. Any thoughts or experience would be helpful. Added some background: my farm was once much larger and we have water rights and a 30hp surface water pump that has its own transformer/service. The power company has increased the cost for this pump 4x each month and I don't really need this much water (I can flood 2 fields out of 5 in 4 hours) I just need enough to keep the fields green so that's why I am thinking about a change to a submersible the power savings will pay for a new pump in less than 1 year.
Turning comments into an answer, probably an answer that could stand some editing when I get a tuit that's round, per Ed's request.
Jet pump to submersible is, in my opinion, a no-brainer. Back in "the day" you were more likely to have a motor failure and having the motor accessible made sense, despite inefficiency and a painful priming process to make the stupid things work. In the modern era, if you need to move water more than 27 feet up (where straight suction will do the job) you want a submersible pump. They are simple, reliable, and efficient. They are kept cool by being in the well.
In the current era you want a 2-wire pump. In the "old days" common wisdom was that you wanted a 3-wire so the capacitor was accessible. With modern parts, you are better off paying for less wire and often smaller wire as well, unless your pump needs and power feed suggest an actual 3-phase pump; but folks tend to cling to the past on this front. Where possible, you also want at least 2 inches between the bore/casing size and the pump size (i.e. 6" bore, 4"pump) to make installation and removal easier.
After 5 or 10 years, consider buying a replacement pump and putting it on the shelf so you don't panic when the first one expires. They don't live forever, and not having to panic-shop for one that ships yesterday can affect the price you pay significantly. That may cost you the relatively short warranty period (typically a year or two) while it sits on the shelf, but the trade-off can be worth it.
With a 4" bore, if you can't find a 2" pump, (they do exist) at least look for a 3" pump (more common, but still not as common as the 4" flavor.)
As Ed already mentioned in his answer I was commenting on, you want the "doilies" to center the pipe and wire, you want to use double hose clamps (and I'll add that you want the barrels of those clamps on opposite sides of the pipe, and if your barbed fitting is long enough, go ahead and use 3.)
In MY climate area, unless you are coming into a heated well-house, you also need a "pitless adapter" to go out the side of the well casing below frost line.
I advise bonding the well casing into the electrical grounding system. In my particular setup it also made lots of sense and cost little extra to drive a few ground rods into the bottom of the well power feed trench along the way. Wires to the well-head in Sch. 80 conduit so they don't have to be dug up ever again.
You need to take care not to scrape the insulation off the wires as you are feeding the unwieldy "snake" into the well, and at whatever point you need to remove it, when removing it as well.
I personally choose to add lightning suppressors to the well head and power feed, as it can be one of the more affected systems when lightning visits - not that anything will withstand a direct strike, but suppression can help equipment survive surges, and when the equipment is inconveniently down a hole, the cost is not very significant, to my thinking.
Depending on the layout of your power and water systems, it can make sense to use a relay to operate the pump from the pressure switch, rather than using the pressure switch directly - in my particular set-up that saves about 100 feet of power-carrying wire - your situation may vary significantly, and it's not usually something you HAVE to change when replacing a pump, rather than putting one in the first time.
Having an ammeter (of the "sensing coil that the wire goes through" flavor for not impacting the reliability of the power connection with an "in-line" meter) permanently connected costs a few bucks extra but can provide some useful info on how the pump is operating, if money is not super-tight.
This might not be any major insight but at least some food for thought.
I think when the efficiency pays for the submersible quickly, it's a no-brainer - you want the submersible.
The submersible is generally better made, benefits from running cool, tolerates debris, generally low maintenance.
When you do have to service it, the submersible is a pain because you have to pull it out of the ground, but the jet pump is a pain because you have to prime it. I'll call that a tie.
Like so many things it comes down to time and money. The submersible is higher initial cost, the jet pump is higher ongoing cost. In some cases where it doesn't run much and electricity is cheap, the submersible may never pay for itself over the life of the pump. But it sounds like in your case you won't have to wait long for the payoff.
In some industrial settings I see people not even think about the cost of the electricity - that comes out of someone else's budget and they want the cheapest possible up front cost, period. Of course there are situations where someone can't afford the better pump today, so they have to take the cheaper option.
But in your case it's a fast payoff so I think the choice is clear, get the submersible.
Well since not much advice (pun intended) . I let the bounty expire. But I did move forward with the submersible.
The first thing I would suggest someone check is there well shaft, I purchased everything and just went for the upgrade. My well shaft was curved and we almost gave up on getting the pump in. I ended up flattening the wiring chase down the side of the pump after the 4th try got it in and flushed the shaft for an hour then compled replumbing , putting the pressure switch and gauge in the lines then the pump controller. One thing I found on my jet pump setup that the suction line way undersized and this may have explained the low flow rate on this system compared to the mfg pump charts. But submersible pumps are more efficient so I think I made the right choice at this time.
Just to point out the parts of a submersible that will be different. The submersible requires 3 or 4 wires and a splice kit as the splice will be under water the wire length will be the depth of the well + the distance to the location the pressure switch and controller will be mounted. A single pipe from the pump to the head where a jet has 2 so a single main hole cap with 1 or 2 smaller ports should be used. Next a length of poly rope. Tie to the pump for removal, (I think this is a big one because many years ago the pipe had failed in a well and we had to pull the pump by its wiring.) A torque arresting device this reduces stress on the pipe and may have been the reason the pump that the line broke it did not have one. Spacers that attach to the pipe and keep the wiring contained and the pipe in the center of the shaft. The same pressure switch and gauge can be used but if mounted on the pump you will need some T's the size of your main line then Bush them down to 1/4 " if standard size. The poly supply line and adapters from the original pump could be used I guess but I replaced everything, from the pump to poly a threaded metal barb fittings with 2 hose clamps a good idea. At the top another barbed fitting with hose clamps and then the conversion back to PVC and connect everything up. I hope this helps someone else may be thinking about doing this. My cost in parts for everything was 720$ my power draw with a slightly larger pump is only .1 amp more than before but my flow rate was well over 2x, I only checked for an hour as the well cleaned up in just a few minutes a true test runs for 3 hours, I will verify this summer. If anyone can think of things I did not mention please comment this is all I can think of at this time.