If you need to make the motor wires longer, it's what you need to do. It's just a good idea to use a heavy gauge wire, if lengthening the wires over the stock length. Of course, the best thing to do is to place the esc in a place where the existing wires will reach.

You can't lengthen the motor wires, so you'll have to make the esc wires longer. I'd unsolder the existing leads and solder in new ones.