Coach Lancaster has called up uncapped Northampton Saints backs Luther Burrell, 25, and Stephen Myler, 28, as replacements.
Lancaster said: "Both played well in the second half of the season and they've both got a great opportunity to put a marker down for the future on tour in Uruguay and Argentina.
"Our commiserations go to Alex Goode and Joel Tomkins. It's disappointing that they have to miss out but they have both had excellent seasons and I am sure they will be back in contention next season."
Goode has been ruled out of the tour with a shoulder injury while Tomkins has an ankle complaint.
England have also called up Exeter Chiefs scrum-half Haydn Thomas and Sale Sharks lock Kearnan Myall, who are both uncapped, to the squad preparing to face the Barbarians on 26 May, when they will field a team without players who feature in the Premiership final on the previous day.