Multiple possibilities.
You could go with a bigger pump. You could go with a second pump, and (ideally, but it's costly, but the cost comes with better reliability) a float switch setup that powers each pump alternately for low water (so one pump isn't sitting there doing nothing all the time until it doesn't work) and both pumps when water gets higher. If you have problems with the power going out during rain events there are battery and (if municipal water is available) water-powered backup sump pumps.
Might be the power of the pump, might be internal wear of the pump parts, might restrictive plumbing limiting the output (I can't begin to guess how many times I've see a sump pump with a 1.5 or 2 inch output choked down to 1" pipe "because it's cheaper".)
As far as I can infer (letters before numbers don't quite match current products, and the numbers are not quite clear) that appears to be a 1/3 HP Zoeller pump with a 1.5" discharge pipe connection, rated for 43 gallons per minute at 5 feet of head. If it has to pump up a lot higher, flow will be reduced, possibly drastically. If the pipe is not 1.5 inches, flow will be reduced. If you get 80 gallons per minute in when the basement is flooding, you need more pump capacity.
Due to design of the pump itself, you can get cases where a 1/3 HP pump would be fine, but one optimized for more head (height it lifts water, and pipe-friction backpressure) may be needed, since a pump designed for a lot of flow at low head is impacted heavily by additional head, and a pump designed for additional head may pump a lot more water at greater head with its different design, on the same power, even though it would pump less at lower head. So don't just look at pump horsepower, especially if your water needs to go up 10+ feet or has a very long pipe.
I've also seen cheap sump pumps where the float will stick and not turn the pump on, sometimes, but not always. I think that's less likely for the type you show.
Depending on terrain, you may or may not be able to greatly reduce the load on the sump pump by providing a gravity drain to daylight. That requires somewhere downhill you can run a pipe to, so it doesn't work if you're in a flat area.
Depending where the water comes from, you may be able to reduce the load (even in a flat area) by altering the grade around the house so water on the surface runs away from the house, not towards it or nowhere. Only takes about 1/8" per foot.
If you don't have gutters, or you do but the downspouts are not routed away from the house before dumping, or they need repair/cleaning, that can help. For that matter, if the sump discharge is too near the house you can end up pumping the same water in circles.
