Diagram for the desired solution, on the shelf:

  V1 V2

In that order you can see that the pages in each book are in this order:

  |    V1    |    V2    |
  +----------+----------+
  |9876543210|9876543210|

(0-indexing of the pages for fun, plus it fit better, also reminded me of annoying protocol specs that mix 0- and 1-based indices with different elements)

The first page of V1 is the rightmost page (shelved) of Volume 1, and the last page of V2 is the leftmost page (shelved) of Volume 2. So the bookworm ends up going only through the covers. Having volumes shelved in order from left-to-right is conventional in left-to-right languages since that's the same direction we read, and you'd want to "read" through the titles to find the volume you wanted.