Is this perhaps what you are looking for?

In[1]:= E^(I x Subscript[p1, m]-I x Subscript[p1, \[Mu]]-I x Subscript[p2, m]-I x Subscript[p2, \[Mu]]) /. 
 x*Subscript[symbol1_,symbol2_]->Subscript[\[Omega],Subscript[symbol1,symbol2]]t-Subscript[symbol1,symbol2]r

Out[1]= E^(
 I (-r Subscript[p1, m] + t Subscript[\[Omega], Subscript[p1, m]]) - 
 I (-r Subscript[p1, \[Mu]] + t Subscript[\[Omega], Subscript[p1, \[Mu]]]) - 
 I (-r Subscript[p2, m] + t Subscript[\[Omega], Subscript[p2, m]]) - 
 I (-r Subscript[p2, \[Mu]] + t Subscript[\[Omega], Subscript[p2, \[Mu]]]))