A whole house demand water heater has a flow control, so a constant pressure pump isn't going to help hot water flow.
All submersible pumps have a maximum pressure, meaning each hp and wet end combination has a differet maximum pressure. So you could say the maximum pressure of submersible pumps varies widely. Those here saying what you now believe and are afraid of, really should look up the pump chart for the pump instead of making blanket statements. Plus, PE pipe comes in various pressure ratings; 75, 100, 125, 160 and 200 psi.
You'll do better with a CSV than variable speed pump and save a bunch to buy it and if it needs to replaced some day. Those pumps are quite pricey.
Your power cable may be worn and that could be tripping the breaker and you wouldn't have to replace the pump.