It sounds like the speed control is a VFD, Variable Frequency Drive. I am told they are extremely noisy. A freind of mine sells these - all very reputable brands. They can be had with the bare essentials for speed control or fully equipped including Radio Frequency Interference suppression equipment. The difference in cost is profound. As an example he said he could sell me a 3 hp, 3 phase controller without enclosure, reactors, etc for $150 for use at home (on machine tool) but warned me that my neighbors would hate me because of the interference. The same drive, with enclosure, disconnect and equipped for suppression, was near $600.
You might contact the pump and drive mfrs. I am told that 'line reactors' are what an engineer might mention in a specification to be sure that some kind of RFI suppression is supplied.