The right way to change customized publish sort slug with out injury website positioning?

I would like to alter the construction of the taxonomy which holds an inventory of merchandise, truly I’ve this implementation:

http://instance.com/watches-product/class/product-name/

however this ought to be:

http://instance.com/watches/product/class/product-name/

So truly I’ve to separate watches-product into watches/product, is feasible do that with out lose the search engine marketing indexability?

That is the present code:

register_taxonomy('wpsc_watch_product_category', 'wpsc_watch_product', array(
    'hierarchical' => true,
    'query_var' => 'watch_product_category',
    'rewrite' => array(
        'slug' => 'watches-product'
    ),
    'labels' => $labels,
));

register_post_type('wpsc_watch_product', array(
    'capability_type' => 'publish',
    'helps' => array('title', 'editor', 'thumbnail', 'page-attributes'),
    'hierarchical' => true,
    'public' => true,
    'show_ui' => true,
    'show_in_nav_menus' => true,
    'labels' => $labels,
    'exclude_from_search' => false,
    "publicly_queryable" => true,
    'rewrite' => array(
        'slug' => __('watches-product', "instance") . '/%class%',
        'with_front' => true
    ),
    'taxonomies' => array('wpsc_watch_product_category'),
));

After this alteration (even when is feasible) I would really like that when an consumer go to the web page:

http://instance.com/watches-product/class/product-name/

the location will redirect him routinely to:

http://instance.com/watches/product/class/product-name/

Thanks prematurely