I'd make sure that the metal well casing is used as a grounding electrode and is properly bonded to the service entrance. This is, after all, a metal underground water pipe (probably much longer than 10 feet).

I think I'd also recommend that the motor be checked for proper grounding and would not rely on any raceway to provide the equipment ground (pull in an equipment grounding conductor).

Tom

Few things are harder to put up with than the annoyance of a good example.