To make room on the 40-man roster for Wilson, Arizona transferred right-handed pitcher Bronson Arroyo, who had Tommy John surgery, to the 60-day disabled list on Monday.
Ahmed finished fifth in the Pacific Coast League with a .312 average, and hit four homers with 47 RBIs. He also batted .228 with four RBIs in 19 games with Arizona.
Chafin went a combined 9-7 with a 4.08 ERA in 26 games between Double-A Mobile and Reno. He made his debut with the Diamondbacks on Aug. 13, pitching five scoreless innings against Cleveland.
Wilson hit .267 with three homers and 38 RBIs in 76 games with Reno.