Breaker getting tired?
How about there maybe being a problem with the pump?
The control panel ought to have a sticker or at least manuals for the pumps, giving you the normal FLA. Otherwise, the size of the contactor can give you an idea of the maximum amount of current the panel can handle. Personally, I'll bet you're exceeding the proper limits.
Grinder pump or not, the first likely cause of troublr is stringy material getting into the pump and wrapping itself around the shaft. If the pump is 3 phase, you can run it backwards and see if that clears the problem.
Next on the list are bad bearings on the pump. When you pump the pit down, you'll likely hear noise once the motor is exposed. Alternatively, you might be able to feel vibrations as the pump runs.
There's no avoiding someone getting down in the pit. If that someone is you, consider getting vaccinated against hepatitis.