Hi,
Siemens have a good protection relay Siprotec 7UM62 but there are a lot more. GE Multilin 789 is also a good and easy one. Futher there are relays from ABB and Beckwith.
And i can recommend you also a Rotor Earth Fault relay these things ar not so expensive and are easy and handfull.
Hi fish22
If you have the equipment to overhaule and test these pumps you could do this. But it's always good to let look a specialist to it.
But it's very cool to do. Disconnect everything, clean, put everything back and then make some characteristics and test runs.
Good luck
Ray