I installed a 3/4 horsepower convertible jet pump to replace one that the impeller failed in, after a few days of good operation the pressure switch line ruptured and leaked.. I quickly replaced it with the one off the old pump.. which cured the leak.. now the pump motoe seems to stay very hot when it shuts off, taking 15 minutes or more to coo down, and I am wondering why the pressure switch line burst.. especially on a new pump.. any thoughts? Pressure is set at 20-50

First thing I'd look at was the pressure at which the pump is cutting off. If may be that the switch is set too high. I could see that causing the pump to run at too high a load to get pressure to that point. Might also explain the ruptured line to the switch.

I might add that I realize you have a 30/50 switch, but I'd still look at the gauge to see where the pump is actually cutting off.

Check your pressure tank as well. If the pump is indeed cutting on at 30#, then the tank pressure should be set to 28#. Do this with the power turned off and pressure drained to zero by opening a low level faucet.

One more thing. With water running, be sure the pump is not short cycling. I doubt it is since you mention that it will stay off for for at least 10 or 15 minutes cooling down, but open a faucet and watch the pressure gauge as the pump cycles. It should be a long, several minutes climb from 30 to 50, and a likewise several minutes time to go back down to 30 once the pump cuts off.