Fetch reference field as a displayed name REST API

Hi,

I'm trying to fetch data from another dev instance. My question is how to fetch display name model and model category (both are reference field) in asset table. Model and model category remains blank. Both sys_id's between stances are different so I guess I have to use displayed name.

I tried getDisplayName() but it doesn't work. 

try {
    var r = new sn_ws.RESTMessageV2('REST API tests', 'Get Assets');

    var response = r.execute();
    var responseBody = response.getBody();
    var httpStatus = response.getStatusCode();
	
    var parsedData = JSON.parse(responseBody);	
    for (i = 0; i < parsedData.result.length; i++) {
		
        var assets = new GlideRecord('alm_asset');
        assets.initialize();
        assets.display_name = parsedData.result[i].display_name;
        assets.model = parsedData.result[i].model;
        assets.model_category = parsedData.result[i].model_category;
        assets.asset_tag = parsedData.result[i].asset_tag;
		assets.insert();
    }
} catch (ex) {
    var message = ex.message;
}