Enamored takes the preposition of, not with.

From my favorite reference book, A Dictionary of Modern Usage, by Bryan Garner.

How common is this usage error?

Approximate Google search results for "enamored with": 1,160,000

Approximate Google search results for "enamored of": 877,000

Some among the usage police have come to accept "enamored with" given its widespread adoption, but to me Garner is law.