If your wheel track is offset from the center line of the bike a tad you might not notice much difference. However it might tend to put the front wheel track and rear wheel track a little bit at odds and possibly you'll get some scrubbing on one or both wheels that will have them wearing out faster.
However, I doubt you have any doom and gloom or catastrophic scenario. You may not even notice at all. But for what little cost the bike shops around here will deal with wheel issues that don't require new parts, you'd get the best results IMO, if you'd just go to a bike shop and let them get you the correct spacers on that hub and also let them dish the wheel if it needs it.
That said, I would send the wheel back and get the proper wheel if it were my bike. Even if there was a nominal re-stocking fee.