Play a song from the album with the correct artwork.
In the bottom left corner of iTunes you should see the artwork. Click on it,
and it will show another window displaying the artwork.
Click on the artwork in that window and drag it to your desktop.
Highlight all the songs you want in that album by selecting the first song, holding down shift, then select the last song. Right click on the selection, and hit "Get Info." A new window will show up.
In that new window, drag the album art from your desktop to the section that says "Artwork" and make sure the info for "Artist," "Album Name," and "Album Artist," is correct too.
And that's it.