Wellman, 25, has recorded 23 points (seven goals, 16 assists) in 37 games this season with San Antonio of the American Hockey League. He ranked third in points on San Antonio at the time of the trade.
The Brentwood, Calif., native has tallied 13 points (four goals, nine assists) in 41 NHL games with Minnesota from 2009-12, and has recorded 105 points (44 goals, 61 assists) in 136 career AHL games with Houston, Connecticut and San Antonio.
The 6-foot, 185-pound forward was originally signed as an undrafted free agent by Minnesota in March 2010 following two seasons at the University of Massachusetts.
Hamill has registered 22 points (11 goals, 11 assists) and a plus-8 rating in 40 games this season with Hershey of the AHL, good for fourth on the team in scoring. Hamill also leads the Bears with three game-winning goals.
A first-round draft choice (eighth overall) by Boston in 2007, Hamill has played 296 AHL games with Hershey and Providence, totaling 55 goals and 106 assists for 161 points. He has also notched four assists in 20 NHL games.