What size gauge romex to use for a well pump?

We have a well at the deer lease that is has a 3/4 hp pump, that is wired for 220. We have a 6500 kw generator that runs it with no problems. What we want to do is run piece of Romex/wire from the pump site to where we keep the generator. This may sound lazy, but it gets redundent rolling the generator back and forth. Especially in bad weather. We would be talking a distance of no more than 200 feet. Any suggestions? And if you know what the cost would be for the grade of Romex/wire.