Pair Programming is an awful practice.
First, if you insist on Pair Programming, you would loose out on may highly qualified and experienced potential employees who would not like to join your company.
And second — Pair Programming reduces productivity. As for quality, while being more expensive it is not as good as peer code reviews.
Pair Programming is a con that is used by IT consultancy that charge customers for the hours of the “bodies” they sell them, to increase their earnings. It is not a surprise that they are the most vocal companies promoting Pair Programming (see Pivotal or ThoughtWorks).