"Snubber circuit sitting directly at motor is often called 'motor filter'. "
a 1HP circulation motor that was in Auto mode to empty a drain reservoir as it got filled up. Once the motor terminals were fitted with 3-Phase snubbers, the problem never came back.

But still your MCU heating up while hanging is something to analyse further.
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Why snubber ? We have designed and employed plenty of Pump controllers for 3-ph pumps in the industry we use E+H sensors and never had a problem .I just use proper Galvanic Isolation it has got nothing to do with snubber his circuit is faulty thats why his uC is getting heated I bet " like steve says " .