Welcome. My name is ***** ***** would be glad to assist.
If the switch you are referencing, is actually the circuit breaker, then the problem would be with the pump motor.
If there is a control cabinet for the pump, it may have capacitors inside and that could be the issue.
The capacitors help to start and run the motor once up to speed.
If one is bad, it make take too high of current to get the motor up to speed and so it trips the breaker.
If it has a control cabinet, you can open it up and get the make and model , then post the info and maybe the specs will can be obtained and we can look it over for something possible instead of the actual pump motor.
I am sure it is an in ground pump which would take some work to change out, so would like to be sure it isnt something else first.
Let me know what you find and post and we can continue,