You can use indexed assignments:
a = torch.ones(2, 1, 2, 10)
b =  = torch.full((2, 1, 2, 3), 2.0)

xa = torch.empty(2, 1, 2, 13)
xa[:,:,:,[0, 1, 2, 3, 4+1, 5+1, 6+2, 7+2, 8+3, 9+3]] = a
xa[:,:,:,[4, 7, 10]] = b
print(xa)

If your columns are a little larger (say 100 instead of 4 elements), a for loop might also not be too bad.
Best regards
Thomas