Here's what I found. The file ceon_uri_mapping_database_tables.php is in two folders:

/ADMIN/includes/extra_datafiles
/includes/extra_datafiles

The one in the admin folder did not have this define:
define('TABLE_CEON_URI_MAPPING_PRODUCT_RELATED_PAGES_URI_PARTS', DB_PREFIX . 'ceon_uri_mapping_prp_uri_parts');

I checked the 5.0.1 zip from CEON and it's there so I don't know if I mixed something up in the install or if this was a bug from 5.0.0. That's the version installed, not 5.0.1 as I thought.