Focus on the motor "shaft" going from the body of the electric motor into the wet end of the pump. This is where you will see not much of anything, IF all is good, otherwise, you may see evidence of a pump seal leak leaving chemical residue, rust or corrosion, or wetness all of which are evidence of a pump seal leak.
The GFCI tripping indicates water getting back into the pump motor causing an electrical fault. The solution = new pump/motor.