Sounds like a classical Right Church, Wrong Pew!
Don't feel bad though! We all make honest mistakes! Just the other day when I changed out a junction box with a ton of wires in it, the compressor for a walk in cooler wasn't engaged due to a three phase hookup and two wires were on the same phase. And circumstances precipitated special motivation by an unqualified adopted brother of mine saying it's good when it wasn't. Thankfully all my business is word of mouth and quality comes first. And I love all the people I do work for!
Problem handled in twenty minutes after it was noticed. And the reason for the job was the previous electriction installed an indoor box that was exposed to the weather!
Without going to plumbing terms 101, what you have is a well pump that's making that noise. A sump pump is a whole other system. MORE INTEL AND INPUT!
Sounds like either a starter capacitor on the pump has gone bad, a bad bearing, or wrong wiring, (I read schematics for this stuff. I learned this before my dad died and I quit DeVry). Check the wiring again. The other stuff requires an ex pert. Due to the construction and time, it's cheaper to just change them out. I can get a starter capacitor for a compressor, but Dreisilkers on Roosevelt deals with motors. I am just a little less ex than pert.
If it is a sump, you have an obstruction in the impeller or a bad bearing. If you open it up and spill mineral oil all over the place, well now you know what that is.
Call the pro and get it over with in a half hour. They will tell you in a shake after looking at it. If this was the purpose for starting this quest, you've may have spent more money than you should have allready. Be mindful that this is an instinct. I personally wouldn't hook up a stereo if I couldn't understand the instructions. And from what you've written, I think you might know one or two friends that can if you don't allready. And being one with the family of man, I'll be the first to say "I am not knowing" before wisdom.