Stoves designed for firebricks should have them.
Stove metal can be corroded and burn through if incorrectly used.
This can be caused by poor combustion due to wet wood or poor draught.
As the OP needs more...
I have bought and fitted 4 wood stoves (2 small and 1 cooking range which all came with firebricks as standard) and looked after several others, some of which were heavy cast iron without firebricks but had a longer path for the gasses to get proper combustion.
This youtube video shows one similar to some I used:
And the hunting scenes always give character...
As for burning wet wood, it is the fastest way to damage a woodstove - I had to rebuild one for someone after two seasons - the gasses are seriously corrosive.
This is why everyone who knows what they ate talking about suggest that the wood is dreied for two years before burning. Also, knowing what type of wood you have is crucial : elm is poor to burn while oak (well seasoned) is pure gold.
Here is a list (easy to find others), which defines wood types: