Disconnect the wires from the pressure switch and do the breaker test again as suggested and described above. Then, using your multimeter (homeowners should own one) measure the winding resistance of the motor and the resistance between the wires to the pump and ground. The answer will tell you if the fault is in the wiring down the well or the pump, but may not tell you which it is.
If there is a short circuit or a short to ground then you have a down-hole problem which means that you should call a well service man, unless you are an agressive DIYer.