A ground wire, several ground rods, lightning arrestors, and turning off the breaker are all good ideas. Do as much as you can because if Mother Nature wants to get that motor, there is not much way to stop her. I have seen wells in the middle of the field with no electricity going to them and the wires not attached to anything, and they still get hit by lightning. They tell me lightning doesn’t even have to hit the wires. It can hit the ground ½ mile from the well and still get the motor.