...adjusting cleat position can help alleviate foot pain and numbness?

Conventional wisdom used to suggest positioning the cleat so that the pedal axle lines up with the ball of the foot. Today's new neutral, however, is widely considered to be 5 to 10 millimeters behind the ball of the foot. 

If you feel foot pain or numbness while riding, you might consider sliding your cleats back a bit to take the ball of your foot off the pedal spindle pressure point. 

You may also want to have a comprehensive bike fit done to dial in your riding position, and it's a good idea to have your set up checked regularly because changes in flexibility, injuries and other factors can affect fit.