You might want that 220 volt pump.  For me in the country to water the lawn is very expensive as it is a sub like yours.

A 220 will take 1/2 the amps to run as a 110, I believe. 

Just how much do use the well now and in the future? 

9 our 10 times I build things to small. 

Yes, you will need another 110 line run to your box and prob. a different box.