This code rewrites the slug of the attachment upon uploading to add a prefix (or suffix) to the slug. In that case you have less chance of getting in the way of page slugs in the future.

gistfile1.txt

add_action('add_attachment', function($postId) {
    // get the attachment post object
    $attachment = get_post($postId);
    // get the slug for the attachment
    $slug = $attachment->post_name;
    // update the post data of the attachment with an edited slug
    wp_update_post(array(
        'ID' => $postId,
        'post_name' => 'media-'.$slug, //adds a prefix
        //'post_name' => $slug.'-photo', //adds a suffix
    ));
});