Simple enough, they're called external grounding lugs.
They're found on every pump motor with a metal case. Could be on the top or the back of the motors.
http://spasupport.com/seq/werep/cswerep1.html
3rd photo row down you'll see an example.
and here:
http://spasupport.com/seq/werep/srwerep1.html
Last two photos on the page.
lastly here:
http://spasupport.com/seq/werep/srwerep4.html
3 photos showing separate ground terminals from pump motor.
Standard code requirement is any pump motor (or any other electrical device with a grounded housing) have a separate ground wire (apart from the cord ground) when mounted within 5' of the appliance.
If your motors don't have the copper grounding lugs, you can purchase them from a home supply store and install yourself on just about any screw on the back of the motor housing that's attached to the metal frame. 10 gauge solid copper wire installed between that and the bonding lugs on the spa control should make the inspector smile.