would check engine light come on for water pump problem

Not directly. It might cause a CEL if the engine overheats. Usually bad pumps leak or don't pump enough fluid due to worm impellers. Get your codes read at the parts store to see what is causing your check engine light.

Unfortunatly the CEL light will come on for various reason, a cooling system fault, be it over heating or not heating up to the needed temperature, thus not letting the engine control system to go into closed loop operation, can cause the light to come on. I would suggest getting the truck looked at by a qualifed service tech, pulling the fault code from the computor is only part of the process, pinpoint testing following that is where you will find the root cause of your fault. The parts stores are great at getting the code, but when they erase the fault they also remove any "freeze frame" data that may have been stored. This is information used by the tech to help find the cause of the concern. It is information from various sensors that the processor stores at the time of the fault, for exapmle Engine coolant temperature, which will help to find the fault. Hope this helps a bit.

Yes

My truck was everything ok until we had flood and truck got wet and check engine light came on