Lower arm spray support (hub) broken

My mom was pulling the lower rack out and the lower spray arm was probably up. I think she forced it, and the arm support (hub) broke off. I found out the part number from your website (part 552 - AP2039804). However, I just want to make sure it is the exact piece.
Since only a small portion broke out, the rest of the portion is still in there, and I can’t find a way to take it out. I have tried twisting it, or just pulling it out, but it doesn’t budge at all.
Can you help me in taking it out?

I have attached the pictures of the broken part.

Thanks!

Can you point me to some documentation/diagram as to how do I remove the pump (under the dishwasher)?

Thanks.