iTunes 12 Artwork is on my Mac, but some not iPhone 5

I have the new iTunes 12. And I'm using an iPhone 5.

My iTunes library on my iMac computer has all of my original artwork. When I listen to songs on my iPhone 5, however, some of my original artwork has been replaced by what looks like iTunes Store artwork -- some of it is completely wrong, too (wrong album, wrong compilation, etc.).

It does not appear that my iTunes library artwork has been touched or changed or altered. It's just as the songs appear on my iPhone 5.

Help? Is this a new issue b/c of Apple Music?

I'd really like the artwork I created to appear on my phone, not the INCORRECT artwork that Apple is seemingly choosing for me on the phone.