The pump is a replace only item. I ordered the full assembly because it is a small increase in cost over the bare pump, and it is much easier to install. I removed the wash arm and filters, disconnected the drain hose and electrical connections, and then the assembly, held by three swing clips. Installation the reverse of removal. The assembly slides in from inside the washer, and there is a trick to the positioning, it only passes through in one orientation.
My part was not functional: my evaluation and the service diagnostic indicated a stuck diverter. The new pump was running, but the water was not passing into the wash arm. I called and asked for a warranty replacement, and customer service made it easy. A week later, I got the replacement, installed it easily (practice makes perfect), and the dishwasher now runs like a dream. Thank you, Appliance Parts Pros!