1. Create the word art
2. Right click on the word art
3. Select Format Word Art
4. Select the "Layout" tab
5. Choose "behind text"
6. Type the text you want on top of the word art
7. Select that type and choose a font
8. Center the text on the page
9. Click on the Word Art and drag it to where you want it.

There is an example of this on page one of my gallery.