It's also called a variable speed well pump. My driller told me about it, but he said that they were sensitive to lightening, and didn't recommend it - but that was 4 years ago. The price premium for that system was another thou$and, about a 30% increase over the fixed speed.
My driller did everything from start to finish - drill the well, install the pump, plumb the pump into the system, and hook everything up to electric.
