How does Sticky Fingers' ability work toward Pesci in Golden Wind?
Bucciarati seperated Mario Zucchero's head earlier in the manga with seemingly no effect on his body ¹
Bucciarati also seperated his own body into parts earlier in the same arc which stopped his blood circulation ²
He chose the second option when he ripped Pesci apart. He also beat him to death (which would explain all the blood). After throwing the parts to the river it is not shown whether the pieces came back or not but Pesci is already dead by then.

1: Chapter 462
2: Chapter 497